Amplifying system for ultra high frequencies



April 1951 M. J. o. STRUTT EI'AL 2,549,992

AMPLIFYING SYSTEM FOR ULTRA HIGH FREQUENCIES Filed May 1, 1946 FIGJ FIG. 2

FIGS

INVENTORi MAYIMLIAAN JULIUS OTTO STRUTT ALDERT VAN DER ZIEL BY Z7 Z AGENT Patented Apr. 24, 1951 AMPLIFYING SYSTEM FOR ULTRA HIGH FREQUENCIES Maximiliaan Julius Otto Strutt and Aldert van der Ziel, Eindhoven, Netherlands, assignors, by mesne assignments, to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application May 1, 1946, Serial No. 666,245 In the Netherlands July 31, 1941 Section 1, Public Law 690, August 8, 1946 Patent expires July 31, 1961.

3 Claims.

The specification of copending U. S. application Serial No. 333,088, filed May 3, 1940, which issued as U. S. Patent No. 2,315,296 on March 30, 1943, discloses an amplifying system for ultrahigh frequencies which comprises a discharge tube containing at least a cathode, an input electrode and an output electrode. The cathode is provided with at least two supply conductors completely separated for high-frequencies and is connected, for high frequencies, through the intermediary of one of the supply conductors, to that end of the input impedance which is remote from the input electrode and, through the intermediary of another supply conductor, to that end of the output impedance which is remote from the output electrode.

The above-mentioned U. S. Patent suggests means for compensating in an amplifying" system of the above-mentioned kind the electron damping which occurs between the input electrode and the cathode so that the resulting input damping of the discharge tube is almost zero or negative. More particularly, it is suggested that at least one of the capacities existing between the input electrode and the cathode and between the input electrode and the connection between the cathode and the output impedance is increased. Furthermore, the inductance between the ends of the cathode and their connection to the input and output circuits are also increased. The amount of additional capacitance and inductance so added is determined by the degree of compensation of the input damping to be effected.

In practice it is frequently preferred to increase. only one or both of the said inductances whereas the capacities are maintained at their minimum values in order to reduce the input capacity of the system as much as possible. In this case the desired increase of the inductances can be obtained, at least partly, by increasing the length of the cathode supply conductors in question. It is as a rule impossible to determine beforehand sufiiciently exactly the length of the supply conductors which is required for the purpose. Moreover, upon mounting the components changes occur in the desired length and location of the connecting conductors which bring about corresponding changes in the inductance value.

It follows therefrom that a possibility of adjusting the values of the inductances is desirable. Since extremely small values of the inductances are involved, it becomes difficult from a practical standpoint to provide an increase or decrease thereof after the mounting. Furthermore, to vary the length of the above-mentioned conductors entails drawbacks whereas a variation in length is completely impossible if the additional inductances are incorporated in the tube itself. The present invention has for its object to provide a simple method by means of which the adjustment of the effective inductances may be effected without the above-mentioned inconveniences.

According to the invention, for this purpose the additional inductances incorporated in at least one of the cathode supply conductors are made larger than is necessary for the desired re-generating effect and between the two cathode supply conductors there is provided a coupling which reduces the effective inductances to such a value that the desired regenerating effect on the input circuit is obtained. It is preferred to provide a coupling which has, at least substantially, an inductive character.

The invention will be explained more fully with reference to the accompanying drawing in which:

Figure 1 is a schematic diagram illustrating one embodiment of the invention,

Fig. 2 is a schematic diagram illustrating another embodiment of the invention, and

Fig. 3 is a schematic diagram illustrating a further embodiment of the invention.

Fig. 1 represents an amplifying system which comprises an amplifying tube I having a cathode 2, a control grid 3 and an anode I. Additional electrodes 5 and 6 may be present between the control grid 3 and the anode I. The cathode 2 is provided with two separated supply conductors which terminate outsidethe tube in points A and B respectively. In at least one of the supply conductors there is incorporated an additional inductance, the total self-inductions of the conductors being denoted by LI and L2. Between the control grid 3 and the cathode 2 is provided an input impedance [9 which is connected, through the intermediary of the conductor L1, to the cathode. Between the anode I and the cathode 2 is present an output impedance 20 which is connected to the cathode through the intermediary of the conductor L2. It is assumed that the additional inductance incorporated in at least one of the supply conductors is embodied in the tube 1.

Depending on whether only the conductor L2 or both conductors L2 and L1 carry current, a determined total self-induction of the conductor L2 alone or of each of the two conductors L1 and L2 is necessary to obtain the desired reduction ance of Is is made smaller.

L1 and/or L2 after the components have once.

been mounted. Moreover, the adjustment involved is critical and an excess of only a few" mms. in the length of the conductors may provide too much inductance.

According to the invention, the additional inductance provided in at least one of the cathode supply conductors is made larger than is necessary for the desired re-generating effect whilst the points A and B are interconnected through V the intermediary of an adjustable impedance L3. The inductances of the two cathode supply conductors are partly bridged by this impedance so that the effect thereof is decreased as the impedvalues of L3 the correct re-generating effect may be adjusted after the mounting of the components has once taken place.

The desired adjustment may also be obtained in the manner shown in Fig. 2. This figure represents one embodiment of the invention wherein the impedance L3 has a fixed value. The

points C and D at which this impedance is connected to that end of the input impedance which is remotefrom the input electrode and to that end of the output impedance which is remote from the output electrode are, however, adjustable. By displacing the points C and D relatively to one another, the currents of the input and output circuits are kept separated more or less, a greater or smaller re-generating effect being thus obtained.

In another embodiment of the invention, which is shown in Fig. 3 the fixed points A and B are interchanged with the taps C and D. The operation completely corresponds otherwise to that of the system according to Fig. 2 and needs therefore no further explanation.

The invention ofiers the further advantage that the impedance In, which constitutes ashunt for the inductances of the conductors L1 and L2, may be comparatively large with the result that either the adjustment of this impedance or the place of the taps is not particularly critical. It is evident that if the cathode supply conductor which connects the cathode to the input circuit is not traversed by current the value of the inductance of the conductor L1 as well as the plac of the tap C or A is irrelevant.

It is desirable to form the impedance L3 as aninductance in order to retain the inductive character of the supply conductors and thus to obtain a re-generating effect which is independent of frequency.

We claim: 7 1. A circuit arrangement for the amplification of high frequencies, comprising an electron discharge tube provided with a cathode having two external terminalsa signal input grid and an anode, the cathode having leads comprising inductance elements connected to each of its external terminals, input and output circuits connect- By varying the ed respectively to the input grid and to the anode, one of said inductance elements having an inductance value larger than is necessary to produce a desired regenerative effect on the input circuit of said tube, an inductance component "connected between said cathode terminals, said external terminals, 2. signal input grid and an anode, the cathode having leads comprisinginductance elements connected to each of its external terminals, one of said inductance elements having an inductance value larger than is necessary to produce a desired regenerative effect on the input circuit of said tube, input and output circuits connected respectively to the input grid and to the anode, the grid return of the input circuit and the anode return of the output circuit being connected together by means of an inductance component having a tapping and an adjustable tapping thereon to provide an inductance value at which the desired regeneration efiect is produced, and means to connect said cathode terminals to said tappings.

3. A circuit arrangement for the amplification of high frequencies, comprising an electron discharge tube provided with a cathode having two external terminals, a signal input grid and an anode, the cathode having leads comprising inductance elements connectedto each of its external terminals, input and output circuits connected respectively to the input grid and to the anode, the grid return of the input circuit being connected to one of the cathode terminals, the anode return of the output circuit being connected to the other cathode terminal, one of said inductance elements having an inductance value exceeding the value necessary to produce a pre-- determined regenerative effect, and a variable inductance coupling said one inductance element to the other element and having a value produc ing the predetermined regenerative effect.

MAXIMILIAAN JULIUS OTTO STRUTT. ALDERT VAN DER ZIEL.

REFERENCES CITED The following references are of record in thefile of this patent:

UNITED STATES PATENTS 

